Conventionally a light set is manufactured as a bundle of interwoven wires with a plurality of lampholders containing lamps electrically and physically mounted at suitable locations along the bundle of wires. Manufacturing the light set in this way requires a lot of time and labor and the resulting overall appearance is not very good. The lampholder in this type of light set also requires an interactive connection between the terminals and the wires which means that there is more than one constraint to consider in the circuit design. This constraint defeats the usefulness of the feature. Finally, because each lampholder is connected in series, the failure of any one lampholder or lamp in the entire light string will result in the failure, inoperability and extinguishment of the entire light set.
In view of the foregoing shortcomings, there have been some improvements developed by the industry. For example, Taiwan patent application number 7,329,609 filed suggests the use of an integrated cord to serve the purpose of connecting the wire through the lamp. It also suggested the use of a lampholder having a base with a bottom opening and an end cover with metal prongs or pikes on it. During assembly the wire is passed through the lampholder base and the end cover is installed so that the prongs penetrate specifically furnished insulation layers on the cord and contact the metal conductor core to make the electrical connection.
However, the lamp set of the Taiwan patent application still suffers from a number of deficiencies. Because the operability of the miniature light circuit depends upon the penetration of the metal pikes into the enclosed conductor, there is often a question as to the satisfaction of the requirements of stability and reliability. Indeed, in the packing or operation of such miniature light strings, if the cord is subjected to repeated bending or folding near a lampholder, the string will very often suffer a poor conductivity between the pikes and the core conductor.
Also, according to the circuit design of the Taiwanese patent application, the lamp set is comprised of a parallel connection of a plurality of strings of lamps connected in series. Thus, the burning out of any one particular lamp will not result in the total inoperability of all of the remaining lamps. However, there is also no denying that when one particular lamp of any string fails, all of the other bulbs in that string will also be extinguished.